Botan Cryptographic Library

Botan is a free and open-source cryptographic library written in C++11 that provides a wide range of cryptographic algorithms, protocols, and tools for building secure applications. Originally developed by Jack Lloyd starting in 2000 (originally as OpenCL, renamed to Botan in 2001), Botan is one of the most comprehensive and well-maintained C++ crypto libraries, used in projects like OpenPGP, Bitcoin, and various enterprise security products. Key features: algorithms: symmetric ciphers (AES, ChaCha20, Serpent, Twofish, Camellia, SM4), AEAD modes (GCM, EAX, OCB, CCM, SIV), hash functions (SHA-1/256/384/512, SHA-3, SHAKE, BLAKE2b, Skein, SM3, Streebog), MACs (HMAC, CMAC, Poly1305, GMAC), public-key crypto (RSA, DSA, ECDSA over NIST/Brainpool curves, Ed25519, Ed448, DH, ECDH, X25519, X448, McEliece, Kyber, Dilithium), key derivation (HKDF, PBKDF2, Argon2, scrypt, bcrypt). TLS: full TLS 1.2 and 1.3 (RFC 8446) implementation with support for modern cipher suites, session resumption, OCSP stapling, and certificate verification. DTLS for UDP-based secure communication. X.509: complete X.509 certificate and CRL parsing, generation, and verification. Certificate path validation with custom trust stores. Post-quantum cryptography: Kyber (key encapsulation) and Dilithium (digital signatures) implementations following NIST PQC standardization. FFI: a C API (botan.h) for use from C and other languages, plus language bindings for Python, Go, Rust, JavaScript (Node.js), Ruby, PHP, and Common Lisp. Build system: supports many build options for controlling which algorithms are compiled, enabling small footprint builds for embedded systems. Hardware acceleration: AES-NI, ARM NEON/crypto, RISC-V vector crypto, and POWER8 crypto. Cross-platform: Linux, macOS, Windows, BSD, Solaris. BSD-2-Clause.